Process for the production of hydrocyanic acid



Patented May 3, 1927.

UNITED STATES PATENT o 1,627,144 FFICE.

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PROCESS FOR THE PRODUCTION OF HYDBOCYANIC ACID.

(No Drawing. Original application filed January 28, 1924, Serial No. 689,156. Divided and this applies/- tion filed November 21, 1924, serial No. 751,375, and in Germany December 7, 1922,

This application is a division of our application (589,156, filed January '28, 1924.

It is already known how to produce hydrocyanic acid by passing ammonia and carbon monoxide over catalytically acting substances at higher-temperatures.

The present invention relates to certain improvements for the production of hydrocyanic acid by the process mentioned.

The invention refers more especially to the proportions of the gases introduced into the process in combination with the use of suitable catalysts. Moreover, according to the invention, protecting gases as hydrogen or containing the same may be used advantageously.

The main feature of the invention consists in using considerable excess of carbon monoxide or substances containing the same,'

e. g. generator gas, gas from coking or the like, in'proportion to the ammonia. By working in this way it will be possible to accelerate the desired formation of hydrocyanic acid considerably and to avoid, as far as possible the undesirable decomposition of the ammonia, especially in avoiding too high temperatures. According to the effect of the catalysts used and to the kind of the gaseous initial substances, the excess of carbon monoxide, or of the mixtures of these two respectively will amount to ap-" proximately two to ten times of the ammonia.

The following substances can be used as catalysts in the process in question, e. g. compounds of silicon, titanium, thorium, zirconium, molybdenum, uranium and vanadium, as well as compounds of the grouprelations of the above-mentioned substances.

the volume Furthermore oxides of the elements of rarev with other catalysts. An extraordinary increase of the speed of reaction has been produced, for instance, by the use of a mixture of cerium oxide with aluminium oxide;

especially in the proportion of 2:1. The

catalysts may be used as they are or on car-.

riers, as for instance clay slabs and the like.

The above-mentioned catalysts may further be totally or artly replaced by other substances, especia stance of silicon or titanlum, zirconium or the like, for instance silite or siloxicon (silit or siloxicon). These kinds of carbides act ternal heating may be used for instance in such a manner that the contact-mass is inserted as formed heating body or loosely, for- Instance, in the shape of grains, in an ly by carbides, for ill-- electric circuit. This manner of heating presents the advanta e that the contact-mass can be brought to the desired temperature and maintained simply by regulating. the intensity of the current.

It has further been found that by a considerable addition of hydrogen as protecting gas, that is to so. more than 1 volume for example 2-10 vo umes to 1 volume of ammonia, the undesirable decomposition of ammonia may be avoided as far as possible.v

Beside hydrogen, gases which contain .the

same, as for instance water-gas or gasses and vapours from molasses-waste and the like, may be used as protecting gas. It is especially advisable to work with excess of carbon monoxide and to take care that considerable quantities of this protectin as, for instance of hydrogen, are present. en working with watergas, or gas mixtures which contain comparatively more hydrogen than these substances, it is advisable to use for one volume element of ammonia-gas for instance 5-10 volume elements of water-gas which isapproximately the equivalent to 2.5 to 5 volumes of hydrogen to 1 of ammonia. In the presence of protecting gases e. g. hydrogen, the decomposition of the ammonia, itself under ordinary pressure, is reduced considerably more than when workin only with excess of carbonic oxide gas. e height of temperature depends on the quality of the catalysts, on the kind of bon monoxide in consi erable excess or in reaction-gas, and diluting means, the concentration of the gaseous nitrogen compounds and on the velocity of-flow of the gases. It is generally advisable to select temperatures between 400 and 800 C. Temperatures between 500 and 600 C. are as cially advantageous. I

en working accordin to the invention it is poun s used almost quantitatively into hydrocyanic acid; A further advantage consists in the possibility of workin also moist gases, so that the rocess o preliminary drying the same as been superseded. It is further not necessary that the gas be specially pure.

When observing the above-described working method, viz, the ap lication ofthe carpresence of considerable quantities of protecting gases like hydro en or nitrogen, or these two measures toget er in combinatlon with the avoiding of too high temperatures, it is also possible, as has been found out, to obtain satisfactory outputs in hydrocyanic acid with the aid of other catalysts but those mentioned .above,.the metals or metal 'compounds of the iron-or platinum-group being excluded. The catalysts for instance aluminium oxide, thorium oxide, zirconium oxide or the like, may be used either alone or in mixture with other catalysts, if desired on carriers es ecially in combination with carbides, in which the latter may serve as carriers.

The objections'tothe employment of iron being known, it is advisable to avoid iron and iron com ounds especially also an iron apparatus. he apparatus may preferably consist, for instance, of copper or of ceramic material.

Examples.

31) 3.75 cubic meters of carbon monoxide an 0.75 cubic meters of ammonia gas are conducted at 600 C. over a contact body consisting of thorium oxide which has been precipitated on clay slabs. The output per hour is about 145 grams of hydrocyanic acid and approximately 0.487 cublc meters of unaltered ammonia.

(2) 150 cubic meters of water gas and 15 cubic meters of ammonia gas are conducted at 600 C. over a contact body consisting 1 of cerium oxide spread on silicon-' carbide.

ossible to convert t e nitrogen com- About 4.5 kg. of h drocyanic acid and approximately 10 cu ic meters of unaltered ammonia are obtained Claims:

1. A process for the production of hydrocyanic acid, consisting in causing carbon' monoxide and ammonia to react at hi h temperatures in the presence'of oxides o metals of the 3rd 4th, 5th and 6th grou s, in the presence of more than 1 volume of ydrogen to 1 volume of ammonia.

2. process for the production of hydrocyamc acid, consisting in causing carbon monoxide and ammonia to react at high temperatures in the presence of oxides of metals of the 3rd, 4th, 5th and 6th groups, in the presence of more than 2 volumes of hydrogen to 1 volume of ammonia.

3. A process for the production of hydrocyanic acid, consisting in causing carbon monoxide and ammonia to react at hi h temperatures in the presence of oxides o metals of the 3rd, 4th, 5th and 6th groups, in the presence of 2.5 to 5 volumes of hydrogen to 1 volume of ammonia.

4. A process for the production of hydrocyanic acid, consisting in causin ammonia and an excess of carbon monoxi e to react at high temperatures in the resence of oxper hour.

ides of metals of the 3rd, 4t 5th and 6th groups, in the presence of such quantities of hydrogen that the ammonia is protected by the hydrogen a ainst decomposition.

5. A process or the production of hydrocyanic acid consisting 1n causin ammonia and an excess of carbon monoxi e amounting to several times the ammonia, to react at high temperatures in the presence of oxides of metalsof the 3rd, 4th, 5th and 6th groups, in the presence of such quantities of hydrogen that the ammonia is protected by the hydrogen against decomposition.

6. A process for the production of hydrocyanic acid consisting in causing ammonia and an excess of carbon monoxi amounting to several times the ammonia, to react at high temperatures in the presence of metals of the 3rd, 4th, 5th and 6th groups, in the presence of more than 1 volume of hydrogen to 1 volume of ammonia.

In testimony whereof we afiix our signatures.

GEORG BREDIG. EGON ELUD. 

